Many household electrical appliances need to keep running when a user is sleeping. For example, a fan or an air conditioner needs to be turned on in summer, a humidifier needs to be turned on when the air is dry, an air purifier needs to be turned on when the air quality is poor, and so on.
In the conventional technology, a silent mode is typically provided in a household electrical appliance such as a fan, an air conditioner, a humidifier, an air purifier, or the like. When the user needs to go to sleep, the user may switch the household electrical appliance to the silent mode using a remote controller or through a control panel on the appliance. A household electrical appliance running in the silent mode produces much less noise than when operating in a normal mode.